Accuracy of very low pretest probability estimates for pulmonary embolism using the method of attribute matching compared with the Wells score

Normal D-Dimer Plasma Level in a Case of Acute Thrombosis Involving Intramuscular Gastrocnemius Vein

Venous thromboembolism (VTE) is a major cause of morbidity and mortality among hospitalized patients. Studies have reported an incidence of deep venous thrombosis to be as high as 50%, especially after craniotomy. Several factors are involved in the alteration of the specificity and sensitivity of D-dimer testing. These include symptom duration, the extent of fibrinolytic and thrombosis activity, anticoagulant therapy, comorbidity associated with medical or surgical illness, cancer, inflammatory diseases, old age, postpartum, and pregnancy period, as well as previous VTE. Several studies have shown the high sensitivity of the D-dimer test (>95%) in pulmonary embolism or acute deep venous thrombosis. The cut-off value is usually within the 500 µg FEU/L range, ruling out acute VTE, especially in patients with low or intermediate clinical probability. Patients who present with a high D-dimer level may necessitate an intense diagnostic approach, the pretest probability notwithstanding. Herein, we present a case of a 52-year-old male patient who presented with a normal D-dimer level in deep venous thrombosis.

Personalized risk stratification through attribute matching for clinical decision making in clinical conditions with aspecific symptoms: The example of syncope

BACKGROUND

Risk stratification is challenging in conditions, such as chest pain, shortness of breath and syncope, which can be the manifestation of many possible underlying diseases. In these cases, decision tools are unlikely to accurately identify all the different adverse events related to the possible etiologies. Attribute matching is a prediction method that matches an individual patient to a group of previously observed patients with identical characteristics and known outcome. We used syncope as a paradigm of clinical conditions presenting with aspecific symptoms to test the attribute matching method for the prediction of the personalized risk of adverse events.

METHODS

We selected the 8 predictor variables common to the individual-patient dataset of 5 prospective emergency department studies enrolling 3388 syncope patients. We calculated all possible combinations and the number of patients in each combination. We compared the predictive accuracy of attribute matching and logistic regression. We then classified ten random patients according to clinical judgment and attribute matching.

RESULTS

Attribute matching provided 253 of the 384 possible combinations in the dataset. Twelve (4.7%), 35 (13.8%), 50 (19.8%) and 160 (63.2%) combinations had a match size ≥50, ≥30, ≥20 and <10 patients, respectively. The AUC for the attribute matching and the multivariate model were 0.59 and 0.74, respectively.

CONCLUSIONS

Attribute matching is a promising tool for personalized and flexible risk prediction. Large databases will need to be used in future studies to test and apply the method in different conditions.

Do Gender and Race Make a Difference in Acute Coronary Syndrome Pretest Probabilities in the Emergency Department?

OBJECTIVES

The objective was to test for significant differences in subjective and objective pretest probabilities for acute coronary syndrome (ACS) in a large cohort of chest pain patients stratified by race or gender. Secondarily we wanted to test for any differences in rates of ACS, rates of 90-day returns, cost, and chest radiation exposure after these stratifications.

METHODS

This is a secondary analysis of a prospective outcomes study of ED patients with chest pain and shortness of breath. We performed two separate analyses. The data set was divided by gender for analysis 1 while the analysis 2 stratification was made by race (nonwhite vs. white). For each analysis, groups were compared on several variables: provider visual analog scales (VAS) for likelihood of ACS, PREtest Consult ACS probabilities, rates of ACS, total radiation exposure to the chest, total costs at 30 days, and 90-day recidivism (ED, overnight observations, and inpatient admissions).

RESULTS

A total of 844 patients were studied. Gender information was present on all 844 subjects, while complete race/ethnicity information was available on 783 (93%) subjects. For the first analysis, female patients made up 57% (478/844) of the population and their mean provider VAS scores for ACS were significantly lower (p = 0.000) at 14% (95% confidence interval [CI] = 13% to 16%) than that of males at 22% (95% CI = 19% to 24%). This was consistent with the objective pretest ACS probabilities subsequently calculated via the validated online tool, PREtest Consult, which were also significantly lower (p = 0.000) at 2.7% (95% CI = 2.4% to 3.1%) for females versus 6.6% (95% CI = 5.9% to 7.3%) for males. However, comparing females to males, there was no significant difference in diagnosis of ACS (3.6% vs. 1.6%), mean chest radiation doses (5.0 mSv vs. 4.9 mSv), total costs at 30 days ($3,451.24 vs. $3,847.68), or return to the ED within 90 days (26% each). For analysis 2 by race, nonwhite patients also comprised 57% (444/783) of individuals. Similar to the gender analysis, mean provider VAS scores for ACS were found to be significantly lower (p = 0.000) at 15% (95% CI = 13% to 16%) for nonwhite versus 20% (95% CI = 18% to 23%) for white subjects. Concordantly, objective pretest ACS probabilities were also significantly lower (p = 0.000) at 3.4% (95% CI = 2.9% to 3.9%) for nonwhite versus 5.3% (95% CI = 4.7% to 5.9%) for white subjects. There were no significant differences in outcomes in nonwhite versus white subjects when compared on diagnosis of ACS (3.2% vs 2.4%), mean chest radiation dose (4.6 mSv vs. 5.0 mSv), cost ($3,156.02 vs. $2,885.18), or 90-day ED returns (28% vs. 23%).

CONCLUSIONS

Despite consistently estimating the risk for ACS to be lower for both females and minorities concordantly with calculated objective pretest assessments, there does not appear to have been any significant decrease in subsequent evaluation of these perceived lower-risk groups when radiation exposure and costs are taken into account. Further studies on the impact of pretest assessments on gender and racial disparities in ED chest pain evaluation are needed.

Emergency Department Cardiopulmonary Evaluation of Low-Risk Chest Pain Patients with Self-Reported Stress and Anxiety

BACKGROUND

Chest pain is a high-risk emergency department (ED) chief complaint; the majority of clinical resources are directed toward detecting and treating cardiopulmonary emergencies. However, at follow-up, 80%-95% of these patients have only a symptom-based diagnosis; a large number have undiagnosed anxiety disorders.

OBJECTIVE

Our aim was to measure the frequency of self-identified stress or anxiety among chest pain patients, and compare their pretest probabilities, care processes, and outcomes.

METHODS

Patients were divided into two groups: explicitly self-reported anxiety and stress or not at 90-day follow-up, then compared on several variables: ultralow (<2.5%) pretest probability, outcome rates for acute coronary syndrome (ACS) and pulmonary embolism (PE), radiation exposure, total costs at 30 days, and 90-day recidivism.

RESULTS

Eight hundred and forty-five patients were studied. Sixty-seven (8%) explicitly attributed their chest pain to "stress" or "anxiety"; their mean ACS pretest probability was 4% (95% confidence interval 2.9%-5.7%) and 49% (33/67) had ultralow pretest probability (0/33 with ACS or PE). None (0/67) were diagnosed with anxiety. Seven hundred and seventy-eight did not report stress or anxiety and, of these, 52% (403/778) had ultralow ACS pretest probability. Only one patient (0.2%; 1/403) was diagnosed with ACS and one patient (0.4%; 1/268) was diagnosed with PE. Patients with self-reported anxiety had similar radiation exposure, associated costs, and nearly identical (25.4% vs. 25.7%) ED recidivism to patients without reported anxiety.

CONCLUSIONS

Without prompting, 8% of patients self-identified "stress" or "anxiety" as the etiology for their chest pain. Most had low pretest probability, were over-investigated for ACS and PE, and not investigated for anxiety syndromes.

Comparison of multidetector computed tomography findings with clinical and laboratory data in pulmonary thromboembolism

BACKGROUND

Pulmonary thromboembolism (PTE) is a common disease with a high mortality rate that is difficult to diagnose and treat. Because of the variety of clinical symptoms and signs, it is difficult to diagnose. Therefore, the diagnosis of PTE is mainly confirmed by imaging techniques. The aim of this study was to evaluate whether there is any corelation of the Wells rule, D-dimer and LDH values with computerized tomography pulmonary angiography (CTPA) findings in PTE diagnosis.

MATERIAL/METHODS

A consecutive series of 62 patients, which included 31 males and 31 females, with high/moderate/low risk of embolism according to Wells pulmonary embolism score, selected from the emergency service and/or outpatient clinic, enrolled in this prospective study. The patients with clinical or laboratory findings of elevated D-dimer level or elevated lactate dehydrogenase (LDH) level were suspected of embolism and underwent tomography.

RESULTS

PTE was detected in 26 patients (42%). A significant difference was not detected between tomography finding positive and negative embolisms in the patient group in terms of age or gender distribution (P=0.221 and P=0.416, respectively). No significant difference was detected between tomography finding positive and negative embolisms in the patient group in terms of elevated LDH or/and D-dimer levels (P=0.263 and P=1.000, respectively). The distribution of low-risk-factor patients in the non-embolism group, and the distribution of high-risk-factor patients in the embolism-positive group was statistically significantly high (P<0.001). There was no statistically significant difference between the groups (P=0.053). Correlation test showed no correlation between LDH and D-dimer levels. (r=0.214, P=0.180).

CONCLUSIONS

In conclusion, when a patient presents with chest pain, our carrying out LDH and D-Dimer tests will not exclude PTE without CTPA. However, we suggest that LDH isoenzymes should be studied in further research.

Age and sex-dependent trends in pulmonary embolism testing and derivation of a clinical decision rule for young patients

IMPORTANCE

Despite low prevalence of pulmonary embolism (PE) in young adults, they are frequently imaged for PE, which involves radiation exposure and substantial financial cost.

OBJECTIVE

Determine the use and positive proportions for PE imaging by age, differences in clinical presentation of PE by age and the projected impact of an age-targeted decision rule.

DESIGN

Analysis of two national population-based datasets: the 2009 Nationwide Emergency Department Sample, a 20% sample of US emergency departments (EDs) and the 2003-2006 Pulmonary Embolism Rule-out Criteria (PERC) dataset, a multisite cohort of ED patients with suspected PE from 12 US EDs.

RESULTS

Prevalence of PE was 10 times lower in young patients (18-35 years) than in older patients (>65 years) (0.06% vs 0.60%, p<0.001), but young patients were imaged for PE almost as frequently as older patients (2.3% vs 3.2%). This resulted in a lower proportion of positive examinations in young adults than older adults (2.3% vs 17.4%, p<0.001 in women; 4.0% vs 21.4%, p<0.001 in men). Clinical predictors of PE varied by age. Tachycardia was a significant predictor of PE in older patients (OR: 1.2-1.9, p<0.001), but not young patients. Fever was a significant predictor only in young patients (OR: 1.4-7.2, p<0.01). A modification of the previously described PERC rule to include age-specific risk factors could reduce PE imaging by 51% in young patients, with a missed PE rate of 0.6% in those excluded from imaging.

CONCLUSIONS AND RELEVANCE

Young patients are frequently imaged for PE and have lower positive imaging rates than older patients. After further validation, application of our proposed rule for excluding young patients from PE imaging could reduce imaging, increase the positive rate of imaging and result in a low rate of missed PE among those excluded from imaging.

Effectiveness of d-dimer as a screening test for venous thromboembolism: an update

Venous thromboembolism (VTE) is the leading cause of morbidity and mortality among hospitalized patients. We searched the PubMed database and reviewed the articles published until June 2011. Articles related to the D-dimer and VTE were considered to write this paper. Many factors play a key role in changing the sensitivity and specificity of D-dimer testing, including the extent of thrombosis and fibrinolytic activity, duration of symptoms, anticoagulant therapy, comorbidity due to surgical or medical illnesses, inflammatory diseases, cancer, elderly age, pregnancy and the postpartum period, and previous VTE. Many previous studies have shown that the D-dimer test is highly sensitive (>95%) in acute deep venous thrombosis or pulmonary embolism, usually with a cut-off value of 500 μg FEU/l, which reasonably rules out acute VTE, particularly in patients with low clinical probability (LCP) or intermediate clinical probability. Patients with high D-dimer levels upon presentation may prompt a more intense diagnostic approach, irrespective of pretest probability. Studies performed after a negative D-dimer for 3 months proved the high negative predictive value (NPV) of D-dimer testing together with LCP in patients with suspected VTE. Among oncology patients, D-dimer testing has the highest sensitivity and NPV in excluding VTE. The new cutoff values of D-dimer testing were analyzed in a recent prospective study of pregnant women; they are 286 ng DDU/ml, 457 ng DDU/ml, and 644 ng DDU/ml for the first, second, and third trimesters, respectively.

Evaluation of the usefulness of a D dimer test in combination with clinical pretest probability score in the prediction and exclusion of Venous Thromboembolism by medical residents

Introduction

Venous thromboembolism (VTE) requires urgent diagnosis and treatment to avoid related complications. Clinical presentations of VTE are nonspecific and require definitive confirmation by imaging techniques. A clinical pretest probability (PTP) score system helps predict VTE and reduces the need for costly imaging studies. d-dimer (DD) assay has been used to screen patients for VTE and has shown to be specific for VTE. The combined use of PTP and DD assay may improve exclusion of VTE and safely avoid imaging studies.

Materials and methods

We prospectively used the Wells PTP score and a DD test to evaluate 230 consecutive patients who presented with VTE symptoms. The receiver operating characteristic curve was used to identify a new DD cutoff value, which was applied to VTE diagnosis and compared with the upper limit of locally established reference range for prediction of thrombosis alone and in combination with the clinical PTP score.

Results

We evaluated 118 patients with VTE symptoms fulfilling the inclusion criteria, 64 (54.2%) with clinically suspected deep vein thrombosis (DVT) and 54 (45.8%) with symptoms of pulmonary embolism (PE). The PTP was low in 28 (43.8%) and moderate/high in 36 (56.25%) of the suspected DVT patients, and low in 29 (53.7%) and moderate/high in 25 (46.3%) of the suspected PE patients. Eighteen cases were confirmed by imaging studies: 9 DVT and 9 PE. The agreement between confirmed cases and PTP was significant with PE but not DVT. The negative predictive value for both DVT and PE with current DD cutoff value of <250 μg/L DDU was 100%, whereas with the calculated cutoff the NPV was 88%.

Conclusions

We confirm that PTP score is valuable tool for medical residents to improve the detection accuracy of VTE, especially for PE. The DD cutoff value of 250 μg/L FEU is ideal for excluding most cases of low PTP; however, the calculated cutoff was less specific for the exclusion of VTE.

Multicenter, Randomized Trial of Quantitative Pretest Probability to Reduce Unnecessary Medical Radiation Exposure in Emergency Department Patients With Chest Pain and Dyspnea

Background—

Use of pretest probability can reduce unnecessary testing. We hypothesize that quantitative pretest probability, linked to evidence-based management strategies, can reduce unnecessary radiation exposure and cost in low-risk patients with symptoms suggestive of acute coronary syndrome and pulmonary embolism.

Methods and Results—

This was a prospective, 4-center, randomized controlled trial of decision support effectiveness. Subjects were adults with chest pain and dyspnea, nondiagnostic ECGs, and no obvious diagnosis. The clinician provided data needed to compute pretest probabilities from a Web-based system. Clinicians randomized to the intervention group received the pretest probability estimates for both acute coronary syndrome and pulmonary embolism and suggested clinical actions designed to lower radiation exposure and cost. The control group received nothing. Patients were followed for 90 days. The primary outcome and sample size of 550 was predicated on a significant reduction in the proportion of healthy patients exposed to >5 mSv chest radiation. A total of 550 patients were randomized, and 541 had complete data. The proportion with >5 mSv to the chest and no significant cardiopulmonary diagnosis within 90 days was reduced from 33% to 25% ( P =0.038). The intervention group had significantly lower median chest radiation exposure (0.06 versus 0.34 mSv; P =0.037, Mann–Whitney U test) and lower median costs ($934 versus $1275; P =0.018) for medical care. Adverse events occurred in 16% of controls and 11% in the intervention group ( P =0.06).

Conclusions—

Provision of pretest probability and prescriptive advice reduced radiation exposure and cost of care in low-risk ambulatory patients with symptoms of acute coronary syndrome and pulmonary embolism.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01059500.

Outcomes and radiation exposure of emergency department patients with chest pain and shortness of breath and ultralow pretest probability: a multicenter study

STUDY OBJECTIVE

Excessive radiation exposure remains a concern for patients with symptoms suggesting acute coronary syndrome and pulmonary embolism but must be judged in the perspective of pretest probability and outcomes. We quantify and qualify the pretest probability, outcomes, and radiation exposure of adults with both chest pain and dyspnea.

METHODS

This was a prospective, 4-center, outcomes study. Patients were adults with dyspnea and chest pain, nondiagnostic ECGs, and no obvious diagnosis. Pretest probability for both acute coronary syndrome and pulmonary embolism was assessed with a validated method; ultralow risk was defined as pretest probability less than 2.5% for both acute coronary syndrome and pulmonary embolism. Patients were followed for diagnosis and total medical radiation exposure for 90 days.

RESULTS

Eight hundred forty patients had complete data; 23 (3%) had acute coronary syndrome and 15 (2%) had pulmonary embolism. The cohort received an average of 4.9 mSv radiation to the chest, 48% from computed tomography pulmonary angiography. The pretest probability estimates for acute coronary syndrome and pulmonary embolism were less than 2.5% in 227 patients (27%), of whom 0 of 277 (0%; 95% confidence interval 0% to 1.7%) had acute coronary syndrome or pulmonary embolism and 7 of 227 (3%) had any significant cardiopulmonary diagnosis. The estimated chest radiation exposure per patient in this ultralow-risk group was 3.5 mSv, including 26 (3%) with greater than 5 mSv radiation to the chest and no significant cardiopulmonary diagnosis.

CONCLUSION

One quarter of patients with chest pain and dyspnea had ultralow risk and no acute coronary syndrome or pulmonary embolism but were exposed to an average of 3.5 mSv radiation to the chest. These data can be used in a clinical guideline to reduce radiation exposure.

Clinician gestalt estimate of pretest probability for acute coronary syndrome and pulmonary embolism in patients with chest pain and dyspnea

STUDY OBJECTIVE

Pretest probability helps guide diagnostic testing for patients with suspected acute coronary syndrome and pulmonary embolism. Pretest probability derived from the clinician's unstructured gestalt estimate is easier and more readily available than methods that require computation. We compare the diagnostic accuracy of physician gestalt estimate for the pretest probability of acute coronary syndrome and pulmonary embolism with a validated, computerized method.

METHODS

This was a secondary analysis of a prospectively collected, multicenter study. Patients (N=840) had chest pain, dyspnea, nondiagnostic ECGs, and no obvious diagnosis. Clinician gestalt pretest probability for both acute coronary syndrome and pulmonary embolism was assessed by visual analog scale and from the method of attribute matching using a Web-based computer program. Patients were followed for outcomes at 90 days.

RESULTS

Clinicians had significantly higher estimates than attribute matching for both acute coronary syndrome (17% versus 4%; P<.001, paired t test) and pulmonary embolism (12% versus 6%; P<.001). The 2 methods had poor correlation for both acute coronary syndrome (r(2)=0.15) and pulmonary embolism (r(2)=0.06). Areas under the receiver operating characteristic curve were lower for clinician estimate compared with the computerized method for acute coronary syndrome: 0.64 (95% confidence interval [CI] 0.51 to 0.77) for clinician gestalt versus 0.78 (95% CI 0.71 to 0.85) for attribute matching. For pulmonary embolism, these values were 0.81 (95% CI 0.79 to 0.92) for clinician gestalt and 0.84 (95% CI 0.76 to 0.93) for attribute matching.

CONCLUSION

Compared with a validated machine-based method, clinicians consistently overestimated pretest probability but on receiver operating curve analysis were as accurate for pulmonary embolism but not acute coronary syndrome.

Future developments in chest pain diagnosis and management

Much of the focus of research on patients with chest pain is directed at technological advances in the diagnosis and management of acute coronary syndrome (ACS), pulmonary embolism (PE), and acute aortic dissection (AAD), despite there being no significant difference at 4 years as regards mortality, ongoing chest pain, and quality of life between patients presenting to the emergency department with noncardiac chest pain and those with cardiac chest pain. This article examines future developments in the diagnosis and management of patients with suspected ACS, PE, AAD, gastrointestinal disease, and musculoskeletal chest pain.